Artificial Depth of Field
 

Hi to everyone:

I'm new to the forum, I sent hours last night trawling through some threads, and this is truly an incredible site. I spent a while looking for message boards like this, and now that I've found it I feel a little embarrassed to post. My knowledge is so far behind what everyone talks about here, it's a little intimidating.

That said, I'm going to risk what could be a completely reiculous question...

Having read up on the 35mm adapter for DV cameras, the homemade contraption that projects through a 35mm lens onto a piece of glass which the DV camera is focused on, therefore allowing you to achieve a shallow depth of field. (I saw Ben Winters test footage and was very impressed)

It occured to me that it might be possible to achieve a similar look by artificially blurring sections of the image. While to do this for an entire movie would be painstaking... I can't think of a quicker way than doctoring each individual frame... if you're talking a 5 minute movie... that's not necessarily too long a task.

Has anyone ever tried doing this?

Am I out of my mind considering it?

I myself have considered doing this. It's much less overwhelming doing it on a single image in Photoshop with duplicate layers, lense and gaussian blur, and masks.

I can't imagine doing it for a movie but with the cost of 35mm lenses it might be my only option!

Maybe you could try shooting the whole thing green/bluescreen, and adding DOF in post.

It would be easier to buy/rent/beg/borrow a 35mm adapter. Some of them are around a thousand dollars or less, but the image recorded is flipped. You have to workaround that problem, like turning the viewfinder and shooting backwards.

You could potentially rotoscope relevant shots (so that might be 3 minutes), but isn't your time worth something? It may also be easier to find a cameraperson in your city with the adapter and convince him/her to work for little/no pay if it's an independent/art/not really commercial film.

The Letus35 is only $300.
There is a tutorial online on how to create artificial DOF.
Personally, I think artificial DOF looks terrible.
But basically you use masks to blur the image except for what you want "in focus"

Ive seen homemade 35mm adapters offered for about 250-300, but its just persuading my department at uni to buy one, and they are a sponsored department, so they can only get certain a brand of equipment... and there's no way they'd allow any modifications in the way I've seen some 35mm adapters attached. I will by using their camera unfortunately as I dont have one, and so there's little point me buying an adapter. And being in the UK, I'm not sure if it's possible to rent one from anywhere, or even borrow one.

but then my time should be worth something. You'd think if I spent all the time it woul take to manually alter each frame of a short movie. (I tried out the artificial dof on some photoshop images and it would take 1 hour to do 1 second, roughly, thats 60 hours per minute. at say 5UKP per hour. thats 300UKP, about $500... you know, on minimum wage, I could buy one inside 2 weeks, much less time than it would take to manually do each image, and that way I can do longer films.

I think I was out of my mind for considering it!

Alex,

Yes, I've done a gaussian blur on the background in interview shots to simulate a shallow DOF. Works fine for short stuff, and talking heads. Good for industrial, spots and the like. It's SOP for that sort of work.

Alex,

Glad you came to your senses...! I just spent two hours rotoscoping 42 frames and I was looking around for something to shoot myself with (and it didn't even work that well). Not worth it, especially if the end result is only shallow depth of field. Good luck with your adaptor search, though!

I can think of a quicker way: build a 35mm adapter and use that, LOL.

Seriously, you can build an adapter a hell of a lot faster than doctoring each frame of a five minute movie.

There's also a company that sells an actual screen you hold up behind the subject which blurs out the background. The examples on the website looked promising, but I've never heard anybody discuss it. Perhaps it's totally cheesy. It might work for head shots though. Sorry I can't post a link. Try a google search.

There's some software called "Final Focus" from a Japanese company that seems to work pretty well from the examples I've seen. Check it out:
http://www.reiji.net/ff-e/

I believe this was a technique that Michel Gondry used in Eternal Sunshine of the Spotless Mind.

I think it was in some tracking shots! he used crew to carry the screen behind the actor. They (or the) shot(s) were obviously quite close up as the screen was very big (like a screen door to keep flies out, I think) any wider and it would have been impractical I guess.

So I agree it might work for talking heads, where you only want them in focus and theres no out of focus foreground elements. But it would require either a massive screen for any wider shots, or a movie consisting of close-ups. Otherwise I'd be stuck with an artificial DoF for the close-ups and then infinite DoF for all the wide shots. (Unless did all the wideshots with no kinetic elements. No pans, zooms, dollies, or moving cast. That way I could do a Photoshop job that was consistent to the entire shot, and quickly too, I'd guess it'd only take a half hour to do 5 or 6 seconds.

Speaking of crazy ways to avoid just getting a job and buying an adapter, I could make tiny versions of what I want in the foreground (to be out of focus) reeds, or branches, whatever, and then put them right up next to the lens (in a kind of false perspective artificial DoF)!

It looks like I either fork out for the adapter, persuade my department to, or shoot documentary style.

I looked at rental costs, forget that! It seems cheaper to buy them (except for the lenses)

Alex

You kind of are stuck that way anyway. Ever seen a really wide shot, non-closeup, with a 35mm lens, that had a shallow DOF? Me neither. That's because even the few big aperture, short focal length 35mm lenses that do exist, don't really do a heck of a lot for blurring the out of focus portions of the image, because the depth of field is still pretty deep and doesn't "fall off" significantly outside the field of focus.

For example a 20mm F1.8 lens is still about the same DOF as a 50mm lens at F4.5. Not very shallow. That big aperture does make things bright, though.

What you can do, however, is use a wider angle lens and then move in closer. Naturally, the closer you get, the more out of focus the background will be, and the wider angle lens helps counteract how much your subject fills the frame due to being so close.

How do it know?
 

I know how you could do the tricks in After Effects, Photoshop, etc., but how does software like Final Focus perform this trick? How does it seperate what you want and then soften it?

I've gathered from their website that it's really intended for animaters to use when compsiting layered images. This would work I assume if you were using live-action with a greenscreen. But I don't think that their software would work for regular film-makers.

Thanks, Bill:

I don't knwo too much about lenses, so would youmind if I ask you this then:

How do you create a feeling of depth in an image without utilising focus (DoF)?

In films there appears to be a clear z-axis visible in long shots. Wheras Video somehow shortens this into a more 2-dimensional image. Does a wide angle lens create a more clearly defined perspective? And is this the answer?

Thanks.

Alex.